Birch trees are possible sources of ice-nucleating macromolecules (INM). Pollen of birch trees are known to be ice nucleation active and were recently shown to release INM. For our work we examined 30 samples of birch branches, consisting of leaves, secondary wood (brown with no photosynthetic activity), and primary wood (green, photosynthetically active). The samples were milled and extracted aqueously. All samples contained INM. Most samples froze at temperatures comparable to birch pollen.